Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number ST21900389 found under Coupling Shaft Flexible by Bae Systems Information And Electronic Systems Integration I Dba Bae Systems Nor. The National Stock Number assigned to this part is 3010013321396, and the Federal Supply Class is 3010 Torque Converters And Speed Changers. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like ST21900389.